HydroMentia, Inc.

Algal Turf Scrubber


The Algal Turf Scrubber offers unparalleled performance for nutrient pollution control by optimizing algae’s natural capabilities to recover excess nutrients from water.

The Algal Turf Scrubber serves as a culture unit for periphytic algae, some of the most prolific and productive plant species on earth. The diverse nature of these systems, along with the fact that the algae directly remove nutrients from the water, allows the technology to offer unparalleled performance for nutrient pollution control.

Polluted water is conveyed to the Algal Turf Scrubber unit, where it is pulsed in waves across a sloped floway. Algal turf or dense mats of simple algae are cultivated on the surface. As the algae grow, they remove nutrient pollutants (nitrogen and phosphorus) from the water. Algal biomass is then regularly harvested and processed into marketable commodities such as soil-enhancing compost or livestock feed; in the future, the biomass may be used as biofuel feedstock. The harvest of plant biomass maintains the culture units in an accelerated growth phase and provides sustainability as nutrients are continuously recovered and removed from the treatment unit.

In addition to direct plant uptake, the Algal Turf Scrubber is optimized through system design and operational practices to facilitate precipitation of phosphorus into the algal biomass. This increases the system’s ability to capture phosphorus, further enhancing its capabilities as a pollutant recovery tool.

The Algal Turf Scrubber optimizes algae’s natural capabilities to recover excess nitrogen and phosphorus from water and delivers unparalleled performance to meet new federal total maximum daily load (TMDL) regulations.

Polluted water is conveyed to the ATS™, where it is pulsed in waves across a sloped floway. Movement of the water down the floway encourages the growth of periphytic algae, which grows into an algal turf on the surface of the treatment floway. The algae, in turn, absorb excess nutrients and carbon dioxide in the water.

Routine harvesting maximizes algal growth and pollutant recovery. Harvested biomass is recycled into environmentally beneficial end products. Products currently made from algae include soil-enhancing compost and livestock feed. In the future, harvested algae will be used for the production of biodiesel and other energy products.

HydroMentia’s pollution control systems can be designed to reduce pollutants to natural background levels at a fraction of the capital and operating costs of competing technologies. No other technology has been shown to reduce nutrient pollutants to background levels (10-40 ppb total phosphorus) while converting residuals to a marketable commodity.

Passive wetland treatment systems currently serve as the primary technology for regional stormwater treatment to achieve low-level phosphorus standards. However, a number of challenges confront passive wetland systems including: (1) long-term effectiveness at higher pollutant loads (non-sustainability without sediment management); (2) restricted applicability in settings where land is limited; (3) and detrimental impacts to communities when land is taken off the local tax roll and out of productive use.

Algal Turf Scrubber systems minimize these challenges through high hydraulic loading rate capabilities, and the regular recovery and recycling of algal biomass developed during decades of research and implementation.

A recent study by the University of Florida concluded that Algal Turf Scrubber phosphorus treatment costs ($/kg P-removed) for proposed treatment systems in the Lake Okeechobee watershed were 53–69% lower than costs for wetland stormwater treatment areas, even when assigning value to the wetland stormwater treatment areas for water storage and recreational benefits.

HydroMentia’s patented harvesting processes allow efficient and cost-effective biomass removal. HydroMentia conducts the harvesting, and all aspects of system operations are routinely evaluated in order to ensure maximum performance.

The mobile operations department handles every aspect of system maintenance during weekly site visits, and is diligent in addressing any issues as they arise.

Operation and maintenance of HydroMentia’s water treatment facilities is streamlined to allow continual remote oversight; eliminating the need for full-time, on-site personnel and reducing operating costs.

Algal Turf Scrubber systems are optimized to create flow conditions that maximize the nutrient uptake of the algal turf. Optimal hydraulic loading rates for Algal Turf Scrubber systems are typically 40-100 times higher than constructed wetland systems. Higher hydraulic loading results in greater biomass production and higher pollutant removal rates, thus less land is needed.

In typical stormwater applications, Algal Turf Scrubber systems will remove 200-1,000 pounds of phosphorus, and 500-8,000 pounds of nitrogen for every acre of process area. At these rates, Algal Turf Scrubber systems require only 3-5% of the land area of comparable treatment wetlands.

The footprint for a 10 mgd treatment module requires as little as 2.5 acres, making the Algal Turf Scrubber ideal where land is limited.

Algal Turf Scrubber systems offer custom solutions that can be sized to meet nearly any pollution reduction goal and water flow condition.

Individual treatment units are constructed in standard modules from one to 25 mgd. For larger flows, standardized 25 mgd Algal Turf Scrubber units are combined into a single treatment facility that can handle hundreds of millions of gallons per day. This approach further reduces land area requirements while significantly enhancing operational efficiency.

The standard module approach allows implementation of reliable, cost-effective systems customized to site-specific water quality and flow conditions.

Algal Turf Scrubber systems are supported by a 30 year performance record in research and commercial applications.

Since the late 1970s, researchers from around the U.S. have developed the use of Algal Turf Scrubber systems for recovery of excess nitrogen and phosphorus from domestic and agricultural wastewater, and more recently stormwater. These studies repeatedly showed that Algal Turf Scrubber systems were capable of effectively recovering nutrient pollutants for a broad range of water quality conditions.

Today, with advanced design and biomass recovery methods, the Algal Turf Scrubber has the ability to cost-effectively remove nutrient pollutants from impaired surface waters and provide a valuable tool to meet TMDL requirements.

Algal Turf Scrubber systems are available only through HydroMentia.

Decades of research and operation are incorporated into each Algal Turf Scrubber facility design. From system enhancement using patented phosphorus precipitation methods, to patented biomass management techniques, no other periphyton-based technology offers comparable performance and experience. Our Mobile Pilot Units ensure system design is calibrated to on-site conditions, and the company holds exclusive license rights allowing the use of harvested periphytic algae as a livestock feed ingredient.

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